The Catalan question is ancient. It dates back to the 17th century, when tensions first developed between Spain's centre and its periphery. It is also modern: a singularly Iberian expression of the fears, risks and contradictions accumulating across much of Europe amid the current recession. Many young people are emigrating from Spain in search of new horizons. Many Catalans want to emigrate collectively. They have to take the first psychological step – a significant part of the Catalan population already considers itself to be outside Spain – which they now hope to transform into a political and institutional process. It won't be an easy job. Catalonia is too important for Spain and the EU, and it already has many problems.

Catalans have for centuries had the national consciousness of an ancient nation. A nation with its own language, which stretched all the way down the eastern side of the Iberian Peninsula. Between the 8th and 15th century, this peninsular saw three expulsions of the Muslim population by the reconquistas of the west, of the centre and of the east. The reconquistas of the west spoke Portuguese and were the fastest of all. Those in the centre spoke Castilian and achieved the greatest territorial domain. And in the east they spoke Catalan and achieved an important position of strength in the Mediterranean, until Christopher Colombus reached America and the peninsula shifted its focus towards the Atlantic. Three movements of reconquest, three languages, one religion – Catholicism – and the imposition of three medieval kingdoms which ended up crystallising into two modern states: Portugal and Spain. Catalonia could have been the third peninsular state – and it was for a short period in 1641 – but history and geography said no. At that time, if Catalonia had not joined Spain it would have ended up in the hands of France.

This is the political origin of a region that could have been the Holland of the south, if it had arisen after the peace of Westphalia in 1648. Catalonia is not an ethnicity, it is not a race, it is not a relic of the past. It is a language with a wider demographic reach than some official EU languages. It is a culture. It is the stamp of the industrial revolution. It is an economy based on small- and medium-sized industry. It is a geographic proximity to old Europe. It is the Mediterranean. And it is a city: Barcelona. Catalonia is more than Barcelona, but it is above all Barcelona.

Catalonia is 6% of the area of Spain, 16% of the population, 19% of the GDP, 25% of industrial production, 29% of exports. These are the current figures.

Catalonia is big enough to imagine itself as an independent state, but it is in a very complicated sociopolitical situation. Without Catalonia, Spain would find itself in an even worse crisis.

A month ago, in Barcelona, the Spanish minister of justice, Alberto Ruiz Gallardón put it like this: "Without Catalonia, Spain would be obliged to abandon the euro."

In economic and political terms, Catalonia is integral. If it goes, España will become Ex-paña. This helps explain the political tension in the country and Spain's refusal to follow the route the UK has chosen with Scotland. The Spanish authorities argue that the constitutional structure of Spain and the UK are different, so that British laws allow an independence referendum and Spanish laws do not. For there to be a referendum on Catalonia, Spain's 1978 constitution would first have to be reformed and this change would have to be approved in a referendum for all Spain. With all certainty, the response would be negative: no, no and no.

There are other possibilities, however. A non-binding consultation could be held to determine the strength of feeling in the Catalan population. The Spanish government fears losing such a consultation.

The solutions are not easy. Spain returns to its labyrinth. (The Spanish Labyrinth is the title of a history of modern Spain by the British historian, and member of the Bloomsbury Group, Gerald Brenan.)

Consequently, Sunday's regional elections are something like the first phase of the consultation. They are thrilling and have already created great anticipation.

Everyone knows that something will change in Spain, but nobody knows exactly what that change will be.

Spain's twofold crisis – economic and territorial – will become a key issue for Europe. After the peace of Westphalia every European power was involved in the war of the Spanish succession, which put the entire continent on the brink. At the time, Catalonia was on the side of the Hapsburgs, and it lost. On that occasion, England at first supported the Catalans, and then abandoned them.